A fuse is a structure that is blown in accordance with a suitable electrical current. For example, an electrical current is provided through the fuse to eventually provide an open circuit condition. In integrated circuitry memory devices, fuses can be used for activating redundancy in memory chips and for programming functions and codes in logic chips. Specifically, dynamic random access memory (DRAM) and static random access memory (SRAM) employ fuses for such purposes.
Electronic fuses can also be used to prevent reduction of yield, which may be caused by random defects, generated in the manufacturing process. Moreover, fuse links provide for voltage options, packaging pin out options, or any other option desired by the manufacturer to be employed prior to the final processing. This helps increase yield and makes it easier to use one basic design for several different end products.
Some electrically blowable fuses take advantage of the electromigration (EM) effect to open an electrical connection. For example, EM is the transport of material caused by the gradual movement of ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms. In electrically blowable fuses that take advantage of EM effect, such transport of material caused by the gradual movement of ions can open the electrical connection.
However, in a typical e-fuse the EM effect causes undesirable hillocks. More specifically, known e-fuses comprise a two-dimensional dog-bone shape having a small cross-sectional area between large cathode and anode pads. During programming, voids form at the center fuse element due to high current density, and eventually create an electrically open circuit. However, the electromigration causes the conductive material to pile-up and form hillocks at the anode end of the fuse element. Hillock formation is an undesirable effect that has not been exploited for any useful purpose.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.